Hope RX4+ or 105 Callipers

Hydraulics are only as strong as the weakest part of the system - different brake callipers won’t generate any more braking force, unless you start looking at bigger discs or different brake pad compounds.

I think it will be a non issue. I'd ride with the 105s and see what they're like. I'm 15 stone and run BB7s on my gravel/road bike and haven't died yet.

After 2 sets of failed Shimano caliper seals I changed to RX4s. They have been faultless for several years.

Others may have different experiences.

I changed my rear 105 level flat mount caliper for an RX4 when the seals started micro leaking and I had a lack of power / howling until the brakes got hot.

I wouldn’t say the rx4s are anymore powerful to be honest. But hopefully they are more reliable.

For more power your main option is probably bigger rotors and pads with more bite.

Run the 105’s until they die then go RX4.

Had RX4s with GRX vbrifters on a review bike and had no end of trouble with them, calipers have a tiny leak that contaminates pads after a few days riding. Stick with Shimano/Shimano not had an issue with 3 sets of GRX, one 105 with deore calipers. 160mm rotors have plenty of stopping power

Thats surprising, my 105 brakes failed after few hundred miles. Genesis replaced the entire system and they failed again.
I also gave up on the deore brakes on my going to work bikes after multiple replacement calipers, I replace with hope brakes and they have had noproblems.
One of the bikes hanging up in the garage has developed brake problems while it was hanging up doing nothing.

Well they’ll prob need doing anyway at some point, and the hopes have 2 sets of pads. If you sell the 105’s as new you’ll be close to breaking even. They also look ace. I’m sure my Hopes are better than the Ultegra they replaced, but TBF if they didn’t leak I wouldn’t have bothered.
Feel More powerful and better modulation.

As said, the Hopes tend to get fitted when Shimano fail (I did).

Hopes work faultlessly and are beautifully bling. If you want them get them, but you might not need them.

The biggest braking fail I had on a CX bike brakes was fitting super lightweight rotors that cook quickly.

I’d get 105 and if they ever fail, replace the seals with compatible ones from EBay. They’re readily available from various sellers.

Hope are bulky, ugly and expensive in my opinion.
Replacement seals (and pistons) are inexpensive as are replacement transfer port o-rings.

4 bikes, 4 sets of RX4/RX4+ callipers and not a problem with any of them in 30000Km+.

In contrast, I went through 3 XTR callipers in around 2/3rds the distance.

RX4+ callipers ate some of the nicest around, especially if you’re using 160mm rotors. No ugly adaptors.

Weird.

Got 985 and 9020 calipers on a couple of bikes (with GRX STIs) that have been on about 4 other bikes each beforehand. No leaks.

I’ve also been through 3 sets of M9020 and M9120 all with failed callipers. All replaced under warranty all sold and replaced with E4s.

The last thing I want variability in are my brakes. With Shimano it was worse than that - it was more…”will they work this time?” Each time you pulled the lever. Like Russian roulette with half the chambers full. Nope.

I don’t think they are expensive- £85 an end with bleed syringe and two sets of pads per calliper. Surely that’s £40 worth of pads.

Run the 105’s until they die then go RX4.

Shimano products have 2 years warranty so just run them. You might not get in with the new bike so might not keep it two years.

If they develop problems get them replaced under warranty and then sell them new and buy hope.

If you want more stopping power then think about a 180 rotor on the front but I suspect it will be fine as it is for a gravel bike.